Yeah, performance is gonna be about the same, plus the DVD quality on the Radeon is better.
I wouldn't upgrade from that to anything less than a GF3 Ti200, it would be a waste of time.
Unless of course somebody gives you a free GF2 Ultra or something, that would probably outperform the Radeon by a bit, but still lower DVD quality, so if that is an important feature for you, stick with that untill you can consider an 8500 upgrade.
THey should be available in the $100 range using some hot deals at any time now.
j